In order to provide better qualities of service and wider communication ranges between wireless nodes, the concept of relay station has been introduced in network systems. The purpose of deploying relay station or Relay Node (RN) in network system is to extend the serving coverage of base station; hence, user equipment (UE) which is not within the communication coverage of base station can access the services provided by relay node as well via base station.
Wireless network architecture as defined by 3GPP introduces wireless relay node (RN) entity to extend the coverage of base station (evolved Node B or eNodeB or eNB). A long term evolution-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system, considering relaying for cost-effective throughput enhancement and coverage extension. For example, a relay can be deployed at the cell edge where the eNB is unable to provide required radio quality/throughput for the UEs or at certain location where radio signals of the eNB cannot cover.
The Relay Node (RN) forms an independent physical cell. From a user equipment (UE) perspective, the RN is seen as a usual base station. The RN is connected via a wireless link to the base station. The relay node architecture deployment foresees that a RN emulates a base station for the UE, which means that the UE would see the RN as a usual base station. From the network side, the RN is seen as a usual UE by the base station. The base station or eNB to which the RN is connected, is called Donor-eNB (DeNB) hereinafter referred to as Base station or eNB and operates as a usual base station. The deployment of RN in the 3GPP network architecture is described in 3GPP Technical Specification 36.806; “Relay architectures for E-UTRA (LTE-Advanced)”.
In order for the user equipment to receive a service from the network, it needs to establish connectivity via base station, by initiating Non-Access Stratum (NAS) signalling messages with network nodes like Mobility Management Entity (MME) serving the UE. Consequential signalling messages are exchanged between network nodes to allocate bearer resources for UE and RN to service the UE request. The above bearer management procedure can be initiated by UE or the Evolved Packet Core (EPC in terms of 3GPP LTE) or simply the communication network. Similar procedures are followed for managing existing bearers. The managing functions include creating new entry, updating and deleting.
Thus, whenever a UE bearer is created or modified, the RN bearer modify or create procedures may be initiated by the RN. This increases the exchange of messages separately for the UE and for the RN to modify/create a new bearer. Thus additional messages may be exchanged by the RN each time a bearer is created/modified for the UE, leading to delayed access service and as well as backhaul bandwidth is wasted or underutilized. Therefore, there is a need for a bearer management to optimize radio and backhaul resources by effectively setting-up the bearers.